Coordinate conversion for the testing of printed circuit boards

ABSTRACT

An array of spring pin contact elements are arranged in a matrix on a uniform rectangular grid and, through a coordinate conversion interface, provide access to the random-arranged contact points of a single or multiple layer printed circuit board for the purpose of conducting electrical tests. The interface is a transition plate constructed in accordance with the artwork of a given board and comprises a baseplate provided with contact pads on one side having the same random arrangement as the contact points of the board, and corresponding contact pads on the opposite side each positioned at an individual contact location having the same planar coordinates as a particular one of the spring pin contact elements. The corresponding pads are electrically interconnected through the baseplate. The board and the interface are supported on a shiftable platen with the random-arranged pads engaging the contact points, the platen being spaced from and aligned with the spring pin elements such that, upon movement of the platen toward the spring pin elements, the pads on the opposite side of the interface are brought into engagement with the elements of like coordinates.

United States Patent Wickersham [72] Inventor: Price D. Wickersham,Shawnee Mission,

Kans.

[73] Assignee: Brooks Research and Manufacturing, Inc.,

Kansas City, Mo. [22] Filed: Mar. 11, 1970 [21] Appl. No.: 18,486

[52] US. Cl ..339/17 M, 174/685, 324/158 F, 339/18 C, 339/151 B, 339/156R [51] Int. Cl. ..H05k 1/02 [58] FieldofSearch 339/176; 174/D1G. 3,68.5; 29/592, 593; 317/101;

[is] 3,654,585 Apr. 4, 1972 1,236,627 6/1960 France ...317/|01 CE GreatBritain ..339/18 C Primary Examiner-Marvin A. Champion AssistantExaminer-Terrell P. Lewis AnrneySchmidt, Johnson, Hovey & Williams 57ABSTRACT interface is a transition plate constructed in accordance withthe artwork of a given board and comprises a baseplate pro- 1 vided withcontact pads on one side having the same random arrangement as thecontact points of the board, and cor- 324/ 158 F responding contact padson the opposite side each positioned at an individual contact locationhaving the same planar coor- [5 6] References Cited dinates as aparticular one of the spring pin contact elements. The correspondingpads are electrically interconnected UNITED STATES PATENTS through thebaseplate. The board and the interface are sup- 2,878,587 3/1959Jubenville ..339/1s P x ported on a Shiftable platen with therandom-arranged p 3,043,022 7/1962 Crews et al..... ....339/17 0 xengaging the Contact points, the platen being spewed from and 3,205,4699/1965 Frank et al ,339/ 18 C aligned with the spring pin elemen Suchthat, "P mOVe- 3,302,065 1/ 1967 Karol et a1. ..339/18 B X ment of theplaten toward the spring pin elements, the pads on 3,406,368 10/ 1968Curran ..339/l4 R X the opposite side of the interface are brought intoengagement 3,434,208 3/1969 Toomey et al.. ..29/626 with the elements oflike coordinates. 3,453,586 7/1969 Brendlen, Jr. ..339/45 M 7 Claims, 11Drawing Figures FORElGN PATENTS OR APPLICATIONS 1,150,441 10/1958 France339/18 C I y l ,l

ll 1 46 F lllllll ll PATENTEDAPR 41972 3,654,585

m'vg/v'mR. Price D. WIckersham QTTORNEYS:

COORDINATE GONVERSION FOR THE TESTING OF P e. il TED CIRCUIT BOARDS Thisinvention relates generally to the testing of printed circuit boards orthe like and, in particular, to a method and structure for makingelectrical connections to the random-arranged contact points of a singleor multiple layer board.

With the continuing use of printed circuit techniques in theconstruction of electrical apparatus, it has become both desirable andadvantageous to employ an automatic circuit analyzer to test printedcircuit modules prior to assembly of the composite apparatus. This hasled to the recent development of a special fixture for providing accessto the various nodes of multilayer printed circuit boards utilized toform the modules. The access fixture permits electrical contact to bemade to all of the nodes of a board for the purpose of conductinginsulation and continuity resistance tests or general electrical tests.The board to be tested is inserted into the fixture beneath an array ofspring pin contacts with each spring pin contact being aligned with acorresponding node on the board. The board issupported by apneumatically actuated platen which is then caused to shift toward thespring pins to bring the latter into pressure engagement with the nodes.The means by which the platen is actuated is incidental, and may behydraulic or motor-driven through appropriate gearing.

Since the patterns and layouts of the artwork of printed circuit boardspresent a nearly infinite variety of spacings and land routings, it hasbeen necessary to accommodate this variable by providing a differentspring pin array for each artwork to be tested. Such arrays take theform of matrix boxes which are selectively positionable in the accessfixture and are provided with a standard connector to form the interfacebetween the matrix box and the circuit analyzer. This arrangementprovides considerable flexibility when testing boards having differentartwork in that it is only necessary to change matrix boxes to achieveaccess to the different node patterns.

Although the foregoing access approach has proven to be successful fromthe standpoint of operability, it may be appreciated that considerabletooling is required to produce a matrix box for each artworkconfiguration. This involves the construction of spring pin arrayshaving different relative locations of the pins thereof to accommodatethe unique node spacing of each individual artwork configuration.Manifestly, tooling costs and hence the overall cost of the testingequipment and procedure could be materially reduced if a single matrixbox were utilized to provide access to all artwork configurationsregardless of the degree of variance of the patterns and layouts.

It is, therefore, the primary object of the present invention toeliminate the need for providing a specially constructed matrix box topermit access to each artwork configuration in order to therebyfacilitate the testing of multiple layer printed circuit boards bothbefore and after assembly thereof and, therefore, facilitate the testingof printed circuit boards in general including single and multiple layertypes employing integrated circuits or discrete components, and othersimilar electrical circuit structures having accessible contact points.

In accordance with the foregoing object, it is another important aim ofthis invention to provide a method of and structure for, in effect,transferring the random-arranged nodes of printed circuit boards tocontact locations having predetermined planar coordinates such that auniversal array of contact elements in the nature of spring pins or thelike may be employed to provide access to all artwork configurations.

In furtherance of the above aim, it is a particular and important objectof the invention to provide a coordinate conversion interface for use inconjunction with a printed circuit board and the aforesaid universalarray of contact elements, in order that the latter may accommodate andprovide access to any artwork configuration through the use of aconversion interface appropriate to each of the differentconfigurations.

Another important object of the invention is to provide a method andapparatus for making electrical connections to the random-arranged nodesor contact points of a printed circuit board or the like wherein only asingle universal array of contact elements as aforesaid is work of theboard under test.

In the drawings:

FIG. l is a diagrammatic, front view of an access fixture for use inmaking electrical connections to a printed circuit board;

FIG. 2 is an enlarged, top view of the apparatus shown in FIG. I, thelid of the fixture and the cover of the matrix box being removed toreveal the array of spring pins and leads extending therefrom;

FIG. 3 is a fragmentary, cross-sectional, detailed view showing a groupof spring pins in contact with the superimposed transition plateinterface and printed circuit board under test;

FIG. 4 is a fragmentary, bottom view of the matrix box enlarged withrespect to FIG. 2 and showing the uniform grid of spring pins;

FIG. 5 is a fragmentary, top view of an exemplary printed circuit boardand associated transition plate interface on the same scale as FIG. 4,showing the same shifted relative to each other rather than in flieirsuperimposed, operative interrelationship in order to provide a visualcomparison of the configurations of the board and the interface;

FIG. 6 is a fragmentary, bottom view of the same portion of thetransition plate interface illustrated in FIG. 5, and shown on the samescale;

FIG. 7 is a greatly enlarged, cross-sectional, detailed viewillustrating coordinate conversion by the interface;

FIG. 8 is a fragmentary, diagrammatic, top view of a printed circuitboard;

FIG. 9 is a fragmentary, diagrammatic, bottom view of a transition plateinterface for use with the board illustrated in FIG. 8;

FIG. 10 is a fragmentary, transition plate of FIG. 9; and

FIG. 11 is a superimposed, diagrammatic mechanical and electricalschematic illustration depicting the circuit resistances in anelectrical continuity test utilizing the transition plate interface ofthe present invention.

Referring initially to FIGS. 1 and 2, an access fixture 20 isillustrated and comprises an upright, rectangular housing having a pairof sidewalls 22 and a rear wall 24. A horizontal, rectangular frame 26is secured to the sidewalls 22 within the fixture 20 and serves as asupport for a horizontal, vertically reciprocable platen 28 shown in itslowermost position resting on the frame 26. A pneumatic piston andcylinder assembly 30 is mounted on the base of the fixture 20 beneaththe platen 28 and, when actuated, shifts the platen 28 upwardly toward amatrix box broadly denoted 32.

The matrix box 32 has a substantially square base 34 of plexiglass orsimilar material which is supported by a pair of opposed side supportmembers 36 secured to respective sidewalls 22 of the fixture 20 abovethe frame 26. The matrix base 34 is held in a horizontal position inparallelism with the platen 28 and is normally enclosed by a cover 38and an overlying lid 40 of the fixture 20 seen in FIG. 1. A connectorpanel 42 is secured to the rear edge portion of the base 34 and may, forexample, receive a mating plu -in connector (not shown) for the purposeof making electrical connections to a multitude of leads 44 that extendfrom an array of contact elements 46 to the connector panel 42.

The contact elements 46 are best seen in FIGS. 3, 4 and 7. As isapparent in FIG. 4, the elements 46 are arranged in a matrix on auniform rectangular grid, each cluster of four elements 46 defining thecorners of a square. The contact elements 46 are in the nature of springpins projecting vertically downwardly equal distances from the matrixbase 34. To provide a means of mounting the spring pin elements 46 onuniform centers, the base 34 is drilled on such centers and elongated,tubular sockets 48 are inserted into the holes and held by a press fit.As is clear in FIG. 3, the upper end of each socket 48 is provided witha terminal 50 to which a respective lead 44 is connected. In FIG. 7, itmay be seen that the lower end of each socket 438 receives plungerportion of the spring required regardless of the artdiagrammatic, topview of the pin 46. Thus, the pin 46, barrel 51, and spring 52 form acontact assembly which is conveniently inserted into the respectivesocket 48 by a press fit. The spring pins 46 are normally held by thesprings 52 at fully extended positions, the springs 52 permitting thepins 46 to retract under applied upward pressure to form resilientcontacts as will be appreciated hereinafter.

Referring to FIG. 5, one corner portion of a printed circuit board 54 isshown extending from beneath a transition plate 56 which, as will bediscussed, forms a coordinate conversion interface that cooperates withboth the array of spring pins 46 and the printed circuit board 54. Itshould be noted that the board 54 has a characteristic pattern ofartwork that presents a number of random-arranged nodes or contactpoints 58. The board 54 illustrated herein is one of the laminae of amultilayer printed circuit board, it being desired to test the lamina 54prior to assembly of the multilayer board. It should be understood,however, that the lamina 54 is only illustrative of one particular typeof printed circuit board that may be accommodated by the presentinvention, since both single layer boards and multilayer boards afterassembly can be accommodated plus single or multilayer boards havingelectronic components mounted thereon if the application of thetransition plate 56 should be to provide access to the nodes of thefully assembled boards for the purpose of performing tests other thansimple continuity and insulation resistance tests,

e.g., impedance or functional tests.

The transition plate interface 56 comprises a thin baseplate 60 ofinsulating material, such as a thin fiberglass sheet. In use, thetransition plate 56 is horizontally disposed thereby presenting a topside or face seen in FIG. and a bottom side or face seen in FIG. 6.Initially, the baseplate 60 is coated on each side with a layer ofcopper or similar conductive material, each copper layer then beingetched to leave only the contact pads 62 on the bottom side of thebaseplate 60, and the contact pads 64 (and other contact structure to bediscussed) on the top side of the baseplate 60. For purposes ofillustration, it is assumed that the baseplate 60 is translucent; thusthe same is advantageously provided with a pair of register marks 66adjacent two or more corners thereof. Similarly, the board 54 isprovided with a pair of register marks 68 adjacent its correspondingcorners. It may be seen that the register marks 66 and 63 are in theform of a bulls-eye and a right angle corner indication, these marksbeing superimposed in exact register in order to properly position thetransition plate 56 in overlying, superimposed relationship to the board54. The contact pads 62 on the bottom side of the baseplate 60 have thesame random arrangement as the contact points 58 of the board 54;therefore, with the plate 56 and the board 54 in register, the pads 62engage corresponding contact points 58 therebeneath.

It may be appreciated from the foregoing that the bottom side of thebaseplate 60 is etched in a manner to reveal segments of the copperlayer only where the contact points 58 will be presented beneath thecopper segments when the transition plate 56 and the board 54 arebrought into proper register. Accordingly, the segments forming the pads62 are preferably of no greater outside diameter than the correspondingcontact points 58 in order to preclude the possibility of shortingacross other nodes or lands of the board 54. In some instances, it maybe desired to actually reduce the outside diameter of the contact pads62 as compared with the corresponding contact points 58 to increase theallowable tolerances and to minimize the possibility of inadvertentshorting should, for some reason, the transition plate 56 and the board54 be aligned in use in other than perfect register.

In contrast to the random arrangement of the lower contact pads 62, theupper pads 64 are arranged on the same uniform grid as the spring pincontact elements 46. Viewed in terms of a planar coordinate system, theupper contact pads 64 have predetermined planar coordinates selectedarbitrarily with respect to the positions of the lower contact pads 62,the coordinate location of each of the upper pads 64 being identical toa corresponding spring pin contact element 46.

The effect of the transition plate 56 is to achieve coordinateconversion as is best depicted in the simplified illustrations of FIGS.8-10. A portion of the board 54 (FIG. 8) is shown having contact points58a, 58b, 55c and 58d. A pair of lands 70 interconnect points 58a and58b, and points 58c and 56d respectively. Manifestly, if the continuity,for example, of the lands 70 is to be tested, connections must be madeto the contact points 58a-58d.

A corresponding portion of the transition plate 56 (bottom side) isshown in FIG. 9. The contact pads 62a, 62b, 62c and 62d are arranged inthe same pattern as the contact points 5811-58 and, when the transitionplate 56 and the board 54 are in proper register, the pads 62a62d willdirectly overlie and engage the corresponding points 58a-58d. The arrayof crosses 74 shown on the transition plate 56 in FIG. 9 representcontact locations having the same planar coordinates as certain of thespring pins 46 depending from the matrix box 32. In other words, withthe transition plate 56 and the board 54 in register and properlypositioned on the platen 28, these contact locations 74 comprisevertical projections of the axes of the overlying spring pins 46.

The top side of the same portion of the transition plate 56 is shown inFIG. 10. It may be seen that the contact pads 62a62 extend completelythrough the baseplate 60 and are electrically connected withcorresponding upper contact pads 64(1-64. Each of the pads 64a-64d iscentered on a different one of the contact locations 74 and thus servesto effect coordinate conversion by virtue of a transition land 76interconnecting each of the pairs of pads 62a, 64a,- 62b, 64b; 62c, 64c;and 62d, 64d respectively. It is now possible to gain access to thecontact points 58a-58d of the board 54 at four contact locations 74having planar coordinates that are the same as those of four of thespring pins 46. In effect, therefore, as illustrated by the pattern ofcontact locations 74 shown in FIG. 8 on the board 54, the contact points58a-58d are transferred from their random positions to four of thepredetermined locations 74. By virtue of the nature of their respectivefunctions, the top pads 64 are hereinafter at times referred to as thecoordinate conversion pads, while the bottom pads 62 are at timesreferred to as the intermediate pads.

FIG. 7 is a greatly enlarged, fragmentary view illustrating thecoordinate conversion action of the transition plate interface 56. Theintermediate pad 62 is shown directly overlying the correspondingcontact point 58 from which one of the lands 70 extends along thecircuit board 54. In etching the top side of the baseplate 60 of thetransition plate interface 56, a copper segment 80 aligned with the pad62 is left on the top side of the baseplate 60 in order to provide ameans of establishing electrical continuity through the thickness of thebaseplate 60. This is done by drilling a hole through the baseplate 60in alignment with the centers of the pad 62 and the segment 80. Theopening 82 thus formed is plated with a conductive substance 84 such ascopper so that, as illustrated, the pad 62, the segment 80 and theintercommunicating plating 84 in effect become an integral conductivebody. If the pad 62 happened to be positioned at or near a coordinatelocation corresponding to one of the spring pins 46, then the transitionland 76 would not be required (this condition is illustrated for anumber of segments 80 in FIG. 5). However, where a substantial change incoordinate location must be effected as illustrated in FIG. 7, thecoordinate conversion pad 64 is positioned at an adjacent spring pincoordinatelocation and electrically connected to the segment 80 (andhence the intermediate pad 62) by the transition land 76.

In the practice of the present invention, a transition plate interfaceis made for every artwork pattern which it is desired to accommodate,but the matrix of spring pins 46 is utilized to provide access to thecontact points of all circuit boards. In the case of multilayer boards,a different transition plate interface would be utilized to provideaccess to the contact points of each of the laminae for testing prior toassembly. Once assembled into a multilayer board, one or more interfaceswould then be utilized to test the composite board. Testing afterassembly is desired since, during the pressing operation requiredrepresentation of the structural in uniting the laminae, a land maybreak or short to another land or metal chips from drilling may becometrapped within the assembly and cause shorting.

Access to the boards is rapidly achieved through the use of the fixture20. The board under test and its associated interface are positioned inmutual register on the platen 28, the latter being provided withsuitable register marks, guides or the like (not shown) for assuringregistration of the coordinate conversion pads of the interface with theplanar coordinate system of the spring pin matrix. The pneumatic pistonand cylinder assembly 30 is then actuated to shift the platen 28vertically until the coordinate conversion pads are brought to bearagainst the spring pins 46 and the latter partially compress the springs52. The platen 28 is then left in a stationary, elevated position duringthe testing program. The elevated position of the platen 28 is bestillustrated in FIG. 3 where a portion of a row of spring pins 46 areshown in engagement with corresponding pads 64 of the transition plateinterface 56. An automatic circuit analyzer for conducting insulationand continuity resistance tests, for example, is connected to the springpins 46 via the connector panel 42 at the rear of the matrix box 32.

FIG. 11 is an equivalent schematic of the circuit involved in resistancemeasurement, superimposed upon a diagrammatic elements of the circuit.The conditions depicted in FIG. 11 are representative of those betweenany pair of spring pins 6. The resistance of the land 70 on the board 54is to be checked, its resistance being represented by R R and R, are thepin-to-pad contact resistances of the two spring pins 46 and respectiveunderlying pads 64. R and R are the resistances of the two transitionlands 76. R and R are the resistances of the plating 84 through theholes in the baseplate 60. R and R are the butt contact resistances ofthe intermediate pads 62 and respective contact points 58.

In actuality, as may be seenin FIG. 5, the transition lands 76 aresignificantly shorter and wider than the lands 70 of the board 54. Thus,it may be assumed that R,, and R are negligible. Furthermore, since thedistance between each segment 80 and its associated intermediate pad 62is only the thickness of the baseplate 60, the resistances R and R mayalso be considered to be negligible. This leaves R,, R R and R, as themajor series resistances in the circuit between the two spring pins 46,other than the unknown resistance R, of the land 70 to be checked. Sincethese remaining resistances are all attributed to the resistance betweenthe various contact structures of the series circuit, their significancemay be significantly reduced by plating the copper pads of thetransition plate interface 56 with a suitable contact material such asgold, and assuring that the relative positions of the platen 28 (whenelevated) and the matrix box 32 are such as to cause uniform deflectionof the pins 416 against their springs 52 to an extent to establish solidelectrical contact. The terminals 86 in FIG. 11 electrically connectedto the spring pins 46 represent connections to suitable testinginstrumentation such as an automatic circuit analyzer.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is:

1. Apparatus for making temporary electrical connections to amultiplicity of electrical contact points on a printed circuit board orthe like having said contact points arranged in an irregular planarpattern peculiar to a particular type of such boards or the like, saidapparatus comprising:

a set of contact elements including a number thereof at least as greatas said multiplicity but arranged in a fixed, regular, planar, matrixpattern different from said pattern of said contact points and havingpredetermined coordinates in the plane of said set;

a coordinate conversion interface comprising a baseplate of insulatingmaterial having a pair of opposed sides, a first array of contact padson one of said sides including a contact pad for each of said contactpoints respectively and arranged in said irregular pattern peculiar tosaid type,

and a second array of contact pads on the other of said sides includinga contact pad for each of the contact pads of said first array butarranged in said regular pattern, each of said contact pads of saidfirst array being electrically coupled with a corresponding contact padof said second array, each of the contact pads of first array beingpositioned for conductively engaging a corresponding contact point ofsaid board or the like, each of the contact pads of said second arraybeing positioned for conductively engaging a corresponding contactelement;

support means spaced from said contact elements and relatively shiftablewith respect to the latter for receiving said circuit board or the likeand said interface in superimposed relationship to each other with thecontact pads of said first array in conductive engagement withcorresponding contact points of said circuit board or the like and thecontacts of said second array facing said contact elements; and

means for relatively shifting said contact elements and said supportmeans to move the contact pads of said second array into conductiveengagement with the contact elements of like coordinates, whereby toestablish electrical continuity between each of said contact points andan individual contact element.

2. Apparatus as claimed in claim 1, said interface having meansextending through said baseplate thereof electrically interconnectingcorresponding contact pads of said first and second arrays.

3. Apparatus as claimed in claim 2, said interconnecting means includinga transition land on said other side extending between eachinterconnected pair of contact pads which are substantially out ofalignment.

4. Apparatus as claimed in claim 1, said matrix pattern arrangementdisposing said contact elements on the intersections of a uniformrectangular grid.

5. A method of making temporary electrical connections to a multiplicityof electrical contact points on a printed circuit board or the likehaving said contact points arranged in an irregular planar patternpeculiar to a particular type of such boards or the like, said methodcomprising the steps of:

a. providing a set of connection locations including a number thereof atleast as great as said multiplicity but arranged in a fixed, regular,planar, matrix pattern different from said pattern of said contactpoints and having predetermined coordinates in the plane of said set;

b. disposing said board or the like in spaced relationship to said setof connection locations with the plane of said contact points parallelto the plane of said connection locations;

c. interposing between said board or the like and said connectionlocations a pair of spaced, parallel, relatively fixed, planar arrays ofcontact pads with the planes of said arrays substantially parallel tothe planes of said contact points and said connection locations, thefirst of said arrays including a contact pad for each of said contactpoints respectively and arranged in said irregular pattern peculiar tosaid type, the second of said arrays of contact pads including a contactpad for each of the contact pads of said first array but arranged insaid regular matrix pattern, each of said contact pads of said firstarray being electrically coupled with a corresponding contact pad ofsaid second array;

d. moving said arrays jointly to align the contact pads of said firstarray with said contact points and to align the contact pads of saidsecond set with said connection locations; and

e. relatively moving said board or the like, said arrays of contact padsand said connection locations in the direction perpendicular to theirplanes to bring the same together with each contact pad of said firstarray thereof electrically contacting a corresponding contact point ofsaid board or the like and each contact pad of said second array thereofelectrically contacting a corresponding connection location,

6. A coordinate conversion interface for use in making temporaryelectrical connections to a multiplicity of electrical contact points ona printed circuit board or the like having said contact points arrangedin an irregular pattern peculiar to a particular type of such board orthe like from a set of contact elements arranged in a fixed, regular,planar pattern difierent from said pattern of said contact points andhaving predeter-w mined coordinates in the plane of said set, saidinterface comprising:

a baseplate of insulating material having a pair of opposed,substantially parallel sides and adapted to be interposed between saidboard or the like and said set of contact elements, said baseplatehaving openings therein communicating said sides of the baseplate andextending through the contact pads of said first array;

a first array of electrically conductive contact pads on one of saidsides of said baseplate including a contact pad for each of said contactpoints respectively and arranged in said irregular pattern peculiar tosaid type;

a'second array of electrically conductive contact pads on the other sideof said baseplate including a contact pad for each of the contact padsof said first array but arranged in said regular pattern, each of saidcontact pads of said first array being electrically coupled with acorresponding contact pad of said second array,

the contact pads of said first array each being adapted to conductivelyengage a corresponding one of said contact oints while each of thecontact pads of said second array is conductively engaging acorresponding contact element; and

means extending through said baseplate electrically interconnectingcorresponding contact pads of said first and second arrays, saidinterconnecting means including an electrically conductive plating onthe baseplate within said openings and electrically connected torespective contact pads of said first array.

7. A coordinate conversion interface for use in making temporaryelectrical connections to a multiplicity of electrical contact points ona printed circuit board or the like having said contact points arrangedin an irregular pattern peculiar to a particular type of such board orthe like from a set of contact elements arranged in a fixed, regular,planar pattern different from said pattern of said contact points andhaving predetermined coordinates in the plane of said set, saidinterface comprising:

a baseplate of insulating material having a pair of opposed,substantially parallel sides and adapted to be interposed between saidboard or the like and said set of contact elements;

a first array of electrically conductive contact pads on one of saidsides of said baseplate including a contact pad for each of said contactpoints respectively and arranged in said irregular pattern peculiar tosaid type; and

a second array of electrically conductive contact pads on the other sideof said baseplate including a contact pad for each of the contact padsof said first array but arranged in said regular pattern, each of saidcontact pads of said first array being electrically coupled with acorresponding contact pad of said second array,

said contact elements and conductive padsof said second array both beingarranged in the same matrix pattern disposing said elements at theintersections of a uniform rectangular grid and the contact pads of saidsecond array at the intersections of a similar uniform rectangular grid,

the contact pads of said first array each being adapted to conductivelyengage a corresponding one of said contact points while each of thecontact pads of said second array is conductively engaging acorresponding contact element.

1. Apparatus for making temporary electrical connections to amultiplicity of electrical contact points on a printed circuit board orthe like having said contact points arranged in an irregular planarpattern peculiar to a particular type of such boards or the like, saidapparatus comprising: a set of contact elements including a numberthereof at least as great as said multiplicity but arranged in a fixed,regular, planar, matrix pattern different from said pattern of saidcontact points and having predetermined coordinates in the plane of saidset; a coordinate conversion interface comprising a baseplate ofinsulating material having a pair of opposed sides, a first array ofcontact pads on one of said sides including a contact pad for each ofsaid contact points respectively and arranged in said irregular patternpeculiar tO said type, and a second array of contact pads on the otherof said sides including a contact pad for each of the contact pads ofsaid first array but arranged in said regular pattern, each of saidcontact pads of said first array being electrically coupled with acorresponding contact pad of said second array, each of the contact padsof first array being positioned for conductively engaging acorresponding contact point of said board or the like, each of thecontact pads of said second array being positioned for conductivelyengaging a corresponding contact element; support means spaced from saidcontact elements and relatively shiftable with respect to the latter forreceiving said circuit board or the like and said interface insuperimposed relationship to each other with the contact pads of saidfirst array in conductive engagement with corresponding contact pointsof said circuit board or the like and the contacts of said second arrayfacing said contact elements; and means for relatively shifting saidcontact elements and said support means to move the contact pads of saidsecond array into conductive engagement with the contact elements oflike coordinates, whereby to establish electrical continuity betweeneach of said contact points and an individual contact element. 2.Apparatus as claimed in claim 1, said interface having means extendingthrough said baseplate thereof electrically interconnectingcorresponding contact pads of said first and second arrays.
 3. Apparatusas claimed in claim 2, said interconnecting means including a transitionland on said other side extending between each interconnected pair ofcontact pads which are substantially out of alignment.
 4. Apparatus asclaimed in claim 1, said matrix pattern arrangement disposing saidcontact elements on the intersections of a uniform rectangular grid. 5.A method of making temporary electrical connections to a multiplicity ofelectrical contact points on a printed circuit board or the like havingsaid contact points arranged in an irregular planar pattern peculiar toa particular type of such boards or the like, said method comprising thesteps of: a. providing a set of connection locations including a numberthereof at least as great as said multiplicity but arranged in a fixed,regular, planar, matrix pattern different from said pattern of saidcontact points and having predetermined coordinates in the plane of saidset; b. disposing said board or the like in spaced relationship to saidset of connection locations with the plane of said contact pointsparallel to the plane of said connection locations; c. interposingbetween said board or the like and said connection locations a pair ofspaced, parallel, relatively fixed, planar arrays of contact pads withthe planes of said arrays substantially parallel to the planes of saidcontact points and said connection locations, the first of said arraysincluding a contact pad for each of said contact points respectively andarranged in said irregular pattern peculiar to said type, the second ofsaid arrays of contact pads including a contact pad for each of thecontact pads of said first array but arranged in said regular matrixpattern, each of said contact pads of said first array beingelectrically coupled with a corresponding contact pad of said secondarray; d. moving said arrays jointly to align the contact pads of saidfirst array with said contact points and to align the contact pads ofsaid second set with said connection locations; and e. relatively movingsaid board or the like, said arrays of contact pads and said connectionlocations in the direction perpendicular to their planes to bring thesame together with each contact pad of said first array thereofelectrically contacting a corresponding contact point of said board orthe like and each contact pad of said second array thereof electricallycontacting a corresponding connection location,
 6. A coordinateconversion interFace for use in making temporary electrical connectionsto a multiplicity of electrical contact points on a printed circuitboard or the like having said contact points arranged in an irregularpattern peculiar to a particular type of such board or the like from aset of contact elements arranged in a fixed, regular, planar patterndifferent from said pattern of said contact points and havingpredetermined coordinates in the plane of said set, said interfacecomprising: a baseplate of insulating material having a pair of opposed,substantially parallel sides and adapted to be interposed between saidboard or the like and said set of contact elements, said baseplatehaving openings therein communicating said sides of the baseplate andextending through the contact pads of said first array; a first array ofelectrically conductive contact pads on one of said sides of saidbaseplate including a contact pad for each of said contact pointsrespectively and arranged in said irregular pattern peculiar to saidtype; a second array of electrically conductive contact pads on theother side of said baseplate including a contact pad for each of thecontact pads of said first array but arranged in said regular pattern,each of said contact pads of said first array being electrically coupledwith a corresponding contact pad of said second array, the contact padsof said first array each being adapted to conductively engage acorresponding one of said contact points while each of the contact padsof said second array is conductively engaging a corresponding contactelement; and means extending through said baseplate electricallyinterconnecting corresponding contact pads of said first and secondarrays, said interconnecting means including an electrically conductiveplating on the baseplate within said openings and electrically connectedto respective contact pads of said first array.
 7. A coordinateconversion interface for use in making temporary electrical connectionsto a multiplicity of electrical contact points on a printed circuitboard or the like having said contact points arranged in an irregularpattern peculiar to a particular type of such board or the like from aset of contact elements arranged in a fixed, regular, planar patterndifferent from said pattern of said contact points and havingpredetermined coordinates in the plane of said set, said interfacecomprising: a baseplate of insulating material having a pair of opposed,substantially parallel sides and adapted to be interposed between saidboard or the like and said set of contact elements; a first array ofelectrically conductive contact pads on one of said sides of saidbaseplate including a contact pad for each of said contact pointsrespectively and arranged in said irregular pattern peculiar to saidtype; and a second array of electrically conductive contact pads on theother side of said baseplate including a contact pad for each of thecontact pads of said first array but arranged in said regular pattern,each of said contact pads of said first array being electrically coupledwith a corresponding contact pad of said second array, said contactelements and conductive pads of said second array both being arranged inthe same matrix pattern disposing said elements at the intersections ofa uniform rectangular grid and the contact pads of said second array atthe intersections of a similar uniform rectangular grid, the contactpads of said first array each being adapted to conductively engage acorresponding one of said contact points while each of the contact padsof said second array is conductively engaging a corresponding contactelement.